1. Field of the Invention
This invention pertains generally to tools for servicing electric generators and more particularly to a tool for removing the endplate from a WESTAC electric generator.
2. Related Art
Commonly large electric generator stators are made up of a tandem array of iron laminations that are held in compression between endplates. Most generators of that type have through bolts holding the endplates and the laminated core together. The through bolts allow for easy removal and access to the core for field maintenance inspections and servicing. However, WESTAC electric generators, manufactured by Siemens Power Generation, Inc., do not have through bolts. This latter type of electric generators core is held together by 15 key bars or blocks that maintain an endplate in compression against the core laminations. In order to remove the endplate, which is a large Bellville washer, it is necessary to compress and flatten the endplate to relieve the pressure off of the key bars so that they may be removed. The current method of flattening the endplate is by the use of a single four inch by 93 inch diameter plate that weights over 7,000 pounds (3175.14 kg.). FIG. 1 shows a planned view of a skeleton of an electric generator oriented in the vertical position normally used for stacking the laminations, with the prior art compression plate 12 in place. The compression plate 12 is held in position against the endplate 24 by a first end portion of all thread 14. All thread 14 passes through the compression plate 12 and extends past the length of the core where it is captured at a second end by a leverage plate 15 that spans the opposite end of the generator frame. A hydraulic jack 20 fits over the all thread 14 and seats against the compression plate 12. The hydraulic jack 20 is locked in position on the all thread 14 by a jack nut 16 and a thrust washer 18. The hydraulic jack 20 exerts a compressive force on the endplate 24 through a cast iron spider 22 that extends between the back face of the compression plate 12 and the hydraulic jack 20. This current system requires the use of a large overhead crane to position the 7000 lb. (3175.14 kg.) compression plate. In addition, it has only been used in the factory with the WESTAC frame in the vertical position. It could probably be adapted for use in the field with the generator frame in the horizontal position, but extensive modifications would be required to install and use this large compression tool for field applications. Cranes large enough to install the compression tool typically cost upwards of $1,000 (E822.45) per day, so it is important to minimize such auxiliary equipment costs.
Accordingly, an improved tool is desired that will enable compression of a WESTAC endplate without the use of an overhead crane.
Furthermore, a new tool is desired that is easier to use in the field than the methods currently being employed and that will reduce costs.